This invention relates to the use of low grade heat, obtained from below the frost line of the earth, to heat or cool a building.
My prior U.S. Pat. No. 4,476,921 discloses and claims a combination building structure and air circulation means comprising a foundation supporting a building having a floor, sidewalls having air channels therein, a ceiling and a roof, and means for obtaining low grade heat from air or water below the hard frost line at the location of the building, the low grade heat being in the temperature range of approximately 45.degree.-65.degree. F., and means for heating or cooling to the temperature range of approximately 45.degree.-65.degree. F. by heat exchange with the low grade heat in a first heat exchange wherein a liquid that has been circulated below the frost line to collect low grade heat is delivered to a first heat exchanger to provide a first source of heating or cooling to the air circulating within the heat exchanger, and a second heat exchange wherein low grade heat is transferred to ambient air that is circulated through a second heat exchanger and this ambient air is then delivered by conduit means to the first heat exchanger, thereby providing a second source of low grade heat to the air within the first heat exchanger, and circulating the heated or cooled air in the temperature range of approximately 45.degree.-65.degree. F. to the space below and adjacent the floor, the space above and adjacent the ceiling, and within the channels in the walls, thereby providing an insulating sheath of air substantially surrounding but not entering the useable space within the building.
By definition, the term "low grade heat" as used herein denotes heat obtainable from various sources but at levels below the temperature needed for human comfort, i.e. below approximately 65.degree. F. The temperature below the hard frost line in northern regions of the United States remains substantially constant year round, at a low of approximately 45.degree. F. in northernmost states (except Alaska) to 50.degree.-55.degree. F. in the middle states. In southern regions which do not freeze, the ground temperature several feet below ground level remains constant year round at approximately 65.degree. F. The heat that is available from either air or water circulated below ground at depths which do not vary in temperature year round is ideal as the source of low grade heat to be used in accordance with the principles of this invention.
U.S. Pat. No. 4,089,142 discloses a building structure including a concrete slab which forms the building structure foundation which supports the building enclosure mounted thereon and is interposed between the building enclosure and the ground. Means are provided for thermally insulating the periphery of the slab from the ground, downwardly from the surface of the ground to at least the extent of the ground frost line and the placement of a series of edge abutting parallel rows of end-to-end abutting hollow cinder or concrete blocks, in axial alignment underlying the concrete slab and axially aligned in heat transfer relationship therewith and with the ground below the frost line. The hollow blocks form a series of parallel transverse air circulation paths and means are provided for communicating these air flow paths within the blocks to the interior of the building enclosure such that thermal radiation entering the building structure interior and impinging upon the building interior causes heat to be circulated by air flow through the parallel air flow paths within the cinder blocks and within the interior of the building blocks acting as a heat sink.
The aforesaid patent discloses heating of the concrete slab by providing glass windows on the vertical walls of the building structure on the sides facing the sun to permit direct impingement of the sun on the upper surface of the concrete slab and building structure interior to thermally heat air flowing within the building structure by convection.
U.S. Pat. No. 3,527,921 discloses a building structure provided with a peripheral foundation insulated to approximately the depth of minimal seasonal temperature variations. The floor of the building is a concrete slab and sand is provided below the slab with electric heating mats located in the sand approximately one foot below the slab to permit storing heat energy in the sand and in the ground beneath so that electric power can be used to heat the building for substantial periods of time either to take advantage of offpeak power or to minimize the effects of electrical power failures.
U.S. Pat. No. 3,965,694 discloses a system having the capability of being used as both a heating and cooling system. Therein, at least one heat pump is provided to pump heat from a heat source to the air conditioning system to prevent freezing of the system. The heat pump also removes heat from the system, when it is used as a cooling system, and diffuses it into the earth. The earth is also utilized as a source of heat to be supplied to the system.